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Using Tapcons & Split Drive Anchors to Attach Wood Flooring to Concrete

It is still possible to enjoy the beauty of hardwood floors with a concrete slab home. When fastening the sub-floor of a wood flooring system to a concrete slab, one simple option is the use of a concrete fastener. There are a number of different concrete fasteners that can be used for this type of project. The concrete fastener chosen to fasten the sub-floor should have a flat, countersunk head. This will provide a smooth and flat surface to which the finished floor can be fastened. The most commonly used anchors for this application are Tapcon® concrete screws and split drive anchors.

It is important to understand the basic makeup of a flooring system when deciding which fasteners are ideal. In most wood flooring applications, there are wood "sleepers" or a plywood sub-floor attached over a polyethylene/plastic vapor barrier, directly to the concrete slab. The finished wood floor is then attached to these sleepers or sub-floor. The fasteners will be used to attach the wood sleepers to the concrete base material. Because the finished flooring will be attached directly to these wood slabs, it is imperative that the concrete anchor have a flat, countersunk head. This will allow the floor to sit flush against the sleeper or sub-floor.

Powder actuated fasteners can also be used for this purpose but the penetration is often inconsistent, and they have a tendency to split the wood sleepers. Another option is to adhere the sub-floor to the slab with the use of a mastic or glue. The difficulty with this method is providing a completely flat concrete surface. In this instance, flat is not just "level" and can be difficult to achieve.

The thickness of the wood sleeper, or sub-floor, will determine the length of anchor required for installation. Tapcons are Tech Tip:
TAPCON® embedments:
1" minimum
1-3/4" maximum

SPLIT DRIVE embedments:
1-1/8" minimum
available in 3/16" and 1/4" diameters. The 3/16" diameter is available in lengths up to 4", while the 1/4" diameter is available up to 6" in length . The split drive anchor is only available in 1/4" diameter with lengths up to 4".

  • To determine the minimum length of Tapcon® concrete screw required, simply add the thickness of the wood sleeper or sub-floor to the minimum embedment required.
  • To determine the length of split drive anchor to use, add the thickness of the sleeper or sub-flooring to the minimum embedment plus an additional 1/4".

The major difference between these two fasteners is that Tapcons are removable while split drive anchors are permanent fasteners. Removal of split drive anchors will cause damage to the surrounding concrete. Before installation, be certain to consider future changes and developments that may require the removal of the fastener used.

It is also important to consider the unique characteristics and specific needs of the project when deciding on which fastener to use. The following list of features should also be considered during the decision making process.

Pros & Cons of Tapcons and Split Drive Anchors

Tapcons

PROS :
Removable
Available in 3/16" and 1/4" diameters
Acceptable for use in ACQ treated lumber
Available in stainless steel (1/4" diameter only)
Minimal anchor spacing required

CONS:
May strip out if too much torque is applied
Maximum embedment is 1-3/4"

Tapcon® is a brand of concrete screw that is manufactured in the United States. It is helpful to note that Tapcons are also known as:
Concrete screws, the Original Tapcons, Masonry screws, Blue Screws, Self-tapping concrete screws, Consert screws, Confast screws, Kwik-Cons, Con-sert screws, Tappers, Ruff-Nex, Cement screws, Titans, and Stainless steel concrete screws.

Split Drive Anchors

PROS:
Permanent
Anchor size is equal to hole size
Easily sets with a hammer

CONS:
Cannot be used with treated wood
Not available in 3/16" diameter
10 anchor diameter minimum spacing

Split drive anchors are also known by a number of names in the industry. These include:
Split anchors, Countersunk split drive anchors, Spikes, Split bolt anchors, Sup-R-Split, Drive anchors and CSD.

Below are installation instructions for the Tapcon® concrete screw and split drive anchor:

Tapcon® Installation

1. Using a hammer drill and correctly sized carbide tipped masonry bit, carefully drill a hole 1/2" deeper than the Tech Tip:
1/4" diameter Tapcon® requires 3/16" bit

3/16"diameter Tapcon® requires 5/32" bit
recommended anchor embedment through the wood sleeper or sub-floor and into the base material.

2. Clear the hole of all debris.

3. Using a standard drill with the appropriate Phillips socket, drive the concrete screw slowly into the pre-drilled hole until the screw is fully seated and flush with the top of the sub-floor or sleeper.

** Be careful not to over-tighten the screw! This will cause the screw to spin in the hole, stripping the threads.

If you need more detailed step-by-step information, view this Concrete Screw installation video.

Split Drive Anchor Installation

1. Using a hammer drill and a correctly sized carbide tipped masonry bit, carefully drill a pilot hole 1/4" deeper than the recommended anchor embedment through the wood sleeper or sub-floor and into the base material.
Tech Tip:
Anchor size is equal to hole size

2. Clear the hole of all debris.

3. Insert the split drive anchor into the hole.

4. Carefully hammer the anchor into the hole until it is flush with the top of the sub-floor or sleeper.

For more detailed installation information, view this Split drive anchor installation video.

Following these step-by-step instructions, each wood sleeper should be fastened to the concrete base. Once the sub-floor is secure and level, the finished wood floor can then be attached to the sub-floor/sleepers.



 

As with any anchoring project, it is important to keep safety in mind and follow instructions carefully. Always remember to wear safety goggles, handle all tools with extra care and follow all technical specifications. This article is meant to serve only as a basic explanation of concrete fasteners. Always refer to manufacturer's instructions or consult a contracting expert during any anchoring project.

Article Written By:
Mike Pistorino, Vice-President Operations

 

 

 

 


Concrete Fasteners, Inc. has over 40 years of experience selling concrete fasteners. We can ship out one box or a whole pallet of concrete anchors. Our products are of the highest quality... "your satisfaction is guaranteed". We ship all orders the same day the order is received.